Femoral cutting block

ABSTRACT

A cutting block assembly comprising first and second interlocking blocks for resecting a distal femur. The first block has a first surface for providing a guiding surface for making an anterior chamfer cut on the femur and a second surface for providing a guiding surface for making a posterior chamfer cut on the femur. The second block is adapted to detachably couple to the first block. The second block has a first surface for providing a guiding surface for making an anterior cut on the femur and a second surface for providing a guiding surface for making a posterior cut on the femur. In another embodiment, the cutting block assembly is a four-in-one (4-in-1) cutting block assembly comprising a first block and second block attached to each other to form a first slot for making an anterior chamfer cut and a second slot for making a posterior chamfer cut.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation-in-part of U.S. patent application Ser. No. 11/642,355, filed Dec. 20, 2006, the disclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

This application relates generally to the implant of prosthetic joints and pertains, more specifically, to the preparation of the distal femur for the implantation of a femoral knee prosthesis, utilizing a femoral cutting block to assist in establishing the surfaces necessary for locating and securing the prosthesis in place on the femur.

The implant of a prosthetic knee joint requires that the distal femur be prepared to receive the femoral component of the knee prosthesis by cutting the bone of the femur to establish accurately located surfaces. Upon implantation, the femoral component will rest on these surfaces. As used herein, when referring to bones or other parts of the body, the term “proximal” means closer to the heart and the term “distal” means more distant from the heart. The term “inferior” means toward the feet and the term “superior” means towards the head. The term “anterior” means towards the front part of the body or the face and the term “posterior” means towards the back of the body. The term “medial” means toward the midline of the body and the term “lateral” means away from the midline of the body.

Various cutting blocks are available to the surgeon for assisting in guiding a saw blade to make the femoral cuts which establish the desired surfaces. These guides usually have guide surfaces for making four resections and are located and secured on the distal femur, upon an already resected transverse surface on the distal femur. Typically, surfaces are provided for guiding the saw blade during the execution of an axially directed anterior femoral cut, an axially directed posterior femoral cut, an anterior chamfer and a posterior chamfer, all specifically related to the size of the femoral knee prosthesis to be implanted and to the position and orientation of the femoral knee prosthesis on the distal femur. A four-in-one cutting block is a single cutting block for making the four cuts. A four-in-two cutting block comprises two separate blocks for making the four cuts. However, such conventional cutting blocks may exhibit various disadvantages. For example, the two blocks of a conventional four-in-two cutting block are used separately and do not interlock to each other. That is, the first block is used making a first set of cuts comprising the anterior and posterior chamfer cuts and the second block is used for making a second set of cuts comprising the anterior and posterior cuts. The first set of cuts is loosely correlated to the second set of cuts which may decrease the accuracy of the cuts. In addition, these cutting blocks are made of metal which may increase the cost of manufacture. Moreover, because of the high cost of such blocks, they are typically reused for additional surgical procedures. However, this may require sterilization of the blocks which may be costly and inconvenient. In addition, current four-in-one cutting blocks include slots for making chamfer cuts to a femur. However, such cutting blocks are difficult to manufacture requiring expensive equipment and processes to manufacture which makes the blocks expensive to produce. Improvements in cutting blocks and in the manufacture thereof are sought.

SUMMARY OF THE INVENTION

The present application provides a cutting block that may help overcome some of the above-mentioned disadvantages. The cutting block of the present application is a four-in-two (4-in-2) cutting block assembly which may improve the accuracy in the preparation of the distal femur for the implantation of a knee prosthesis. The cutting block assembly comprises a first block for making the anterior and posterior chamfer cuts and a second block for making the anterior and posterior cuts. The first and second blocks interlock which helps correlate the four cuts and improve the accuracy of the cuts. The second block includes extended cutting surfaces which may further help improve the accuracy of the anterior and posterior cuts. In addition, the second block provides a visual indication of the accuracy of the anterior and posterior chamfer cuts before the anterior and posterior cuts are made. Moreover, the cutting block can be made of polymeric material which may help reduce the cost of making the block. In addition, because polymeric material is relatively lightweight compared to metal, the cutting block may be relatively lightweight which may improve the handling of the cutting block during a surgical procedure.

In one aspect of the present application, disclosed is a cutting block assembly comprising interlocking first and second blocks for resecting a distal femur. The first block has a first surface for providing a guiding surface for making an anterior chamfer cut on the femur and a second surface for providing a guiding surface for making a posterior chamfer cut on the femur. The second block is adapted to detachably couple to the first block. The second block has a first surface for providing a guiding surface for making an anterior cut on the femur and a second surface for providing a guiding surface for making a posterior cut on the femur.

In another aspect of the present application, disclosed is a method of resecting a distal femur. The method includes attaching a first block to the distal femur, the first block having a first surface providing a guiding surface for making an anterior chamfer cut on the femur, a second surface providing a guiding surface for making a posterior chamfer cut on the femur, and making anterior and posterior chamfer cuts on the distal femur. The method further includes attaching a second block to the first block, the second block having a first surface providing a guiding surface for making an anterior cut on the femur, and a second surface providing a guiding surface for making a posterior cut on the femur, and making anterior and posterior cuts on the distal femur.

In yet another aspect of the present application, disclosed is a method of resecting a distal femur. The method includes attaching a first block to the distal femur, the first block having a first surface providing a guiding surface for making an anterior chamfer cut on the femur, a second surface providing a guiding surface for making a posterior chamfer cut on the femur. The method further includes attaching a second block to the first block, the second block having a first surface providing a guiding surface for making an anterior cut on the femur, and a second surface providing a guiding surface for making a posterior cut on the femur. The method further includes making anterior and posterior cuts on the distal femur, detaching the second block from the first block, and making anterior and posterior chamfer cuts on the distal femur.

In another embodiment of the present application, disclosed is a four-in-one (4-in-1) cutting block assembly comprising a first block and second block which are attached to each other to form a first slot for making an anterior chamfer cut and a second slot for making a posterior chamfer cut. The first and second blocks are manufactured separately and then attached to each other to form a single cutting block assembly. The blocks can be made using various materials well known in the art. For example, the blocks can be made from a polymeric material using injection molding techniques and attached to each other using an adhesive bond or well known techniques in the art. In another embodiment, the blocks can be made from a metal material using milling techniques and attached to each other using a weld bond, ultrasonic weld or other techniques well known in the art. In other embodiments, the blocks can be attached to each other using mechanical locking means such as clamps, pin/socket arrangements or other locking mechanisms well known in the art. Thus, manufacturing the blocks separately and then attaching them together to form a single cutting block unit reduces the cost of manufacture. In addition, such techniques may provide a surgeon with the flexibility of using an open faced cutting guide or a captured cutting slot during surgical procedures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of the bone cutting blocks in an un-assembled configuration, in accordance with an embodiment of the present application.

FIG. 2 is an isometric view of the cutting blocks of FIG. 1 from a different angle.

FIG. 3 is a detailed isometric view of a first block of the cutting block assembly of FIG. 1.

FIG. 4 is a detailed partial isometric view of a second block of the cutting block assembly of FIG. 1.

FIG. 5A is an isometric view of the cutting block assembly of FIG. 1, in an assembled configuration.

FIG. 5B is a rear view of the second block of FIG. 5A.

FIG. 6 is a detailed partial isometric view of the cutting block assembly of FIG. 5B.

FIG. 7 is a detailed cross-sectional view of the cutting block assembly of FIG. 5B taken along lines A-A.

FIG. 8A is an isometric view and FIG. 8B is a medial view of a distal femur after a distal cut has been made on the surface of the distal femur.

FIG. 9A is an isometric view and FIG. 9B is a medial view showing the first block of the cutting block of FIGS. 1-7 being attached to the distal femur of FIGS. 8A-8B.

FIG. 10A is an isometric view and FIG. 10B is a medial view showing the first block attached to the distal femur of FIGS. 9A-9B in preparation for making anterior and posterior chamfer cuts on the surface of the distal femur.

FIG. 11A is an isometric view and FIG. 11B is a medial view showing the distal femur of FIGS. 10A-10B after the anterior and posterior chamfer cuts have been made.

FIG. 12A is an isometric view and FIG. 12B is a medial view showing the distal femur of FIGS. 11A-11B with the second block being attached to the first block.

FIG. 13A is an isometric view and FIG. 13B is a medial view showing the first and second blocks being interlocked to form a cutting block assembly for making anterior and posterior cuts on the surface of the distal femur of FIGS. 12A-12B.

FIG. 14A is an isometric view and FIG. 14B is a medial view showing the distal femur of FIGS. 13A-13B after the anterior and posterior cuts have been made on the surface of the distal femur.

FIG. 15 is a medial view showing the distal femur of FIGS. 14A-14B after the cutting block assembly has been removed.

FIG. 16 is an isometric view of the bone cutting blocks in an un-assembled configuration, in accordance with another embodiment of the present application.

FIG. 17 is a side view of the cutting blocks of FIG. 16.

FIG. 18 is an isometric view of the second block of the cutting block assembly of FIG. 16.

FIG. 19 is an isometric view of the cutting blocks of FIG. 16 in an assembled configuration.

FIG. 20 is another view of the cutting block assembly of FIG. 19.

FIG. 21 is a medial view of the cutting block assembly of FIG. 20 being attached to a distal femur.

FIG. 22 is a medial view showing the cutting block assembly attached to the distal femur of FIG. 21 in preparation for making anterior and posterior cuts on the surface of the distal femur.

FIG. 23 is a medial view showing the distal femur of FIG. 22 after the anterior and posterior cuts have been made.

FIG. 24 is a medial view showing the distal femur of FIG. 23 with the second block of the cutting block assembly being removed.

FIG. 25 is a medial view showing the distal femur of FIG. 24 with the second block removed in preparation for making posterior and anterior chamfer cuts on the surface of the distal femur.

FIG. 26 is a medial view showing the distal femur of FIG. 25 after the anterior and posterior chamfer cuts have been made on the surface of the distal femur.

FIG. 27 is a medial view showing the distal femur of FIG. 26 after the first cutting block of the cutting block assembly has been removed and the four cuts have been made.

FIG. 28 is an isometric view of a cutting block in an un-assembled configuration in accordance with another embodiment of the present application.

FIG. 29 is an isometric view of the cutting block of FIG. 28 from another angle.

FIG. 30 is an isometric view of the cutting block of FIG. 28 in an assembled configuration.

FIG. 31 is an isometric view of the cutting block of FIG. 30 from another angle.

FIG. 32 is a front view of the cutting block of FIG. 31.

FIG. 33 is a detailed cross-sectional view of the cutting block of FIG. 32 taken along lines B-B.

FIG. 34 is a medial view showing the cutting block assembly of FIG. 33 attached to a distal femur in preparation for making cuts on the surface of the distal femur.

FIG. 35 is an isometric view of a cutting block assembly according to another embodiment of the present application, showing a third block attached to the cutting block of FIG. 28 in an un-assembled configuration.

FIG. 36 is an isometric view of the cutting block assembly of FIG. 35 in an assembled configuration.

FIG. 37 is a front view of the cutting block assembly of FIG. 36.

FIG. 38 is a detailed cross-sectional view of the cutting block assembly of FIG. 37 taken along lines C-C.

DETAILED DESCRIPTION

Referring to FIGS. 1-7, shown is a cutting block assembly generally denoted as 10 comprising a first block 12 capable of interlocking with a second block 14 to form a four-in-two (4-in-2) cutting block for resecting a portion of a bone such as a distal femur. Referring to FIGS. 1-2, the first block 12 is a generally triangular shaped block forming an anterior-chamfer cutting surface 16, a posterior-chamfer cutting surface 18, a contact surface 20 and side surfaces 22. The anterior-chamfer cutting surface 16 provides a guiding surface for making an anterior-chamfer cut on a femur (not shown). The posterior-chamfer cutting surface 18 provides a guiding surface for making a posterior-chamfer cut on the femur. The contact surface 20 includes protrusions 26 adapted to fit into holes in the distal femur to detachably couple the first block 12 to the distal resected surface of a distal femur (not shown), as explained below in further detail. In one embodiment, the protrusions 26 are shown as cylindrical posts but can have other shapes such as square. In one embodiment, the first block 12 also may include angled pin holes 28 extending outwardly from the contact surface 20 to the side surfaces 22. The pin holes 28 are adapted to receive pins (not shown) to more firmly secure the first block 12 to the distal resected surface of the distal femur. The cutting surfaces 16, 18 of the first block 12 form a generally V-shaped portion 13 for coupling to the second block 14, as explained below.

The second block 14 is a generally trapezoidal shaped block with V-shaped portion 15 sized to receive the V-shaped portion 13 of the first block 12. The second block 14 forms an anterior cutting surface 30, a posterior cutting surface 32, contact surfaces 34, 36 and side surfaces 38. The anterior cutting surface 30 provides a guiding surface for making an anterior cut on the femur. The posterior cutting surface 32 provides a guiding surface for making a posterior cut on the femur. The contact surfaces 34, 36 of the second block 14 form the generally V-shaped open-faced portion or channel 15 which is complementary to the generally V-shaped portion 13 formed by the surfaces 16, 18 of the first block 12. In this manner, as explained above, the portion 13 of the first block 12 is capable of fitting within the portion 15 of the second block 14.

One possible feature of the cutting block assembly 10 is an interlocking mechanism for detachably securing the blocks 12, 14 to each other. In a preferred embodiment, the interlocking feature is a slidable coupling mechanism comprising holes 24 of the first block 12 adapted to receive protrusions 44 of the second block 14. Two protrusions 44 extend outwardly from the surface 34 of the second block 14 and one protrusion 44 extends outwardly from the surface 36. In a complementary manner, two holes 24 extend through the surface 16 of the first block 12 and one hole 24 extends through the surface 18 of the first block. The protrusions are adapted to slide into and fit within the holes 24 to form an interlocking feature to detachably couple or interlock the first block 12 to the second block 14. Such an arrangement may provide various advantages. For example, as explained above, the first block 12 provides for anterior and posterior chamfer cuts and the second block 14 provides for anterior and posterior cuts. By using the interlocking feature to interlock the first block 12 with the second block 14, the cutting block assembly 10 allows the four distal femur cuts (anterior-chamfer, posterior-chamfer, anterior, posterior) to be tightly correlated to each other which may help increase the accuracy of the cuts.

Another possible feature of the cutting block assembly 10 is that it provides a mechanism to verify the accuracy of the posterior and anterior chamfer cuts before the anterior and posterior cuts are made. For example, in one embodiment, the second block 14 includes extended portions 30 a, 32 a which extend beyond the contact surface 20 and cutting surfaces 16, 18 of the first block 12, as best shown in FIG. 7. The extended portions 30 a, 32 a include extended portions of contact surfaces 34, 36, respectively, and extended portions of cutting surfaces 30, 32, respectively. As explained below in detail, because the extended cutting surfaces 30, 32, which are part of extended portions 30 a, 32 a, provide increased cutting surface area for making the anterior and posterior cuts which may help improve the accuracy of the anterior and posterior cuts. In addition, the contact surfaces 34, 36, which are part of portions 30 a, 32 a, extend onto the chamfer cuts which may allow a user to verify the anterior and posterior chamfer cuts made with the first block before making the anterior and posteriors cuts with the second block.

Another possible feature of the cutting block assembly is that it can be made of relatively lightweight material which may provide various advantages. In one embodiment, the blocks 12, 14 are made of a polymeric material such as plastic which may help reduce the complexity and cost of manufacturing the block. Moreover, because the blocks are made of a polymeric material, the blocks can be discarded after being used instead of having to sterilize the blocks for subsequent use. However, the blocks 12, 14 can be made of other materials, such as metal, or other materials well known to one skilled in the art. In a preferred embodiment, the cutting surfaces 16, 18, 30, 32 are generally planar and smooth. In another embodiment, the surfaces 16, 18, 30, 32 can be non-smooth with grooves or ridges on the surfaces. In a preferred embodiment, the contact surfaces 34, 36 of the second block 14 are formed with ribs 42 extending into the interior of the block which may help reduce the amount of material and thus improve manufacturability and reduce the cost of manufacture. In addition, the use of less material and/or polymeric material may help make the cutting block more lightweight which may make the cutting block easier to use or manipulate during a surgical procedure.

Another possible feature of the cutting block assembly is that it provides a “keyed” mechanism to help ensure that the blocks are interlocked in a proper manner. In one embodiment, the number and arrangement of the protrusions 44 and holes 24 provide a locking mechanism which requires the blocks 12, 14 to be oriented and coupled to each other in only a single configuration. The first block 12 includes two holes 24 disposed over a single hole 24. In a complementary manner, the second block 14 includes two protrusions 44 disposed over a single protrusion. In this manner, the blocks 12, 14 can be coupled to each other in only one orientation. That is, the anterior surfaces 16, 30 are required to be aligned to each other and the posterior surfaces 18, 32 are required to be aligned to each other. This feature may help reduce the possibility of error during a surgical procedure. However, the number, size and arrangement of the protrusions 44 and holes 24 can be implemented in other ways. For example, the arrangement can be reversed, with one protrusion disposed over the two protrusions and the holes 24 configured in a similar manner.

Referring to FIGS. 3 and 4, shown are detailed views of the first block 12 and second block 14 respectively of FIGS. 1-2. As explained above, the protrusions 44 of the second block 14 are adapted to fit within the holes 24 of the first block 12 to form an interlocking feature to detachably couple or interlock the blocks 12, 14 to each other. The protrusions 44 and the corresponding holes 24 are shown as generally square shaped but can have other shapes, such as cylindrical, as long as they are complementary to provide a relatively secure interlock between the blocks. The protrusions 44 have generally square shaped ramps 44 a on bottom surfaces of the protrusions. In a complementary manner, the holes 24 have generally square shaped ramps 24 a on bottom surfaces of the holes. The protrusions 44 are slightly yieldable to accommodate the ramps 24 a of the holes, as explained below.

Referring to FIGS. 4, 5, 6, shown are detailed views of the first block 12 and second block 14 of FIG. 1 in an assembled configuration. To assemble the blocks 12, 14 to form assembly 10, the blocks 12, 14 are advanced toward each other to permit the protrusions 44 of the second block 14 to be inserted into the holes 24 of the first block 12. The blocks 12, 14 are further advanced toward each other such that the ridges 44 a of the second block 14 contact the ramps 24 a of the first block 12. As the blocks 12, 14 are further advanced toward each other, the protrusions 44 yield upward and away from the ramps 24 a and the ridges 44 a pass beyond the surface of the ramps 24 a and return to their original position. Once the ridges 44 a are positioned behind the surfaces of the ramps 24 a, the protrusions 44 are held in place in the holes 24 to provide a secure detachable coupling or interlock between the blocks 12, 14. To detach the blocks 12, 14 from each other, the blocks are moved away from each other with sufficient force to cause the ridges 44 a to slide over and away from the ramps 24 a thereby freeing the blocks from each other.

Referring to FIGS. 8A-8B to 14A-14B, a description is provided of a surgical procedure for resecting a distal femur 52 of a femur bone 50 using the cutting block assembly 10 of FIGS. 1-7 in accordance with an embodiment of the present application. Referring to FIGS. 8A-8B, the distal femur 52 has an anterior portion 52 a, a medial portion 52 b, a posterior portion 52 c, and a lateral portion 52 d. In an initial step of the surgical procedure, a distal cut is made which involves the resection or removal of a distal bone portion (not shown) from the distal femur 52 leaving behind a generally flat resected distal surface 56. A cutting device (not shown) can be used to remove the distal bone portion using conventional techniques. The cutting device can be a bone cutter such as an oscillating saw or other bone cutting device well-known to one skilled in the art. Once the distal cut has been made, pilot holes 54 can be drilled into the distal surface 56 in precise location and orientation as known to one skilled in the art to accommodate the protrusions 26 of the first block 12 as shown in FIGS. 9A-9B and described below.

FIG. 9A is an isometric view and FIG. 9B is a medial view showing the first block 12 of the cutting block assembly 10 of FIGS. 1-7 being attached to the distal femur of FIGS. 8A-8B. The first block 12 is advanced toward the distal femur 52 with the contact surface 20 of the first block 12 oriented to face the distal surface 56 of the distal femur. The first block 12 is also oriented with the protrusions 26 of the first block being aligned with the holes 54 of the distal surface 56. In addition, the first block 12 is oriented with the cutting surface 16 (labeled “Anterior”) generally facing the anterior portion 52 a of the distal femur 52. The first block 12 is advanced toward the distal surface 56 until the protrusions 26 enter the holes 54 of the distal surface 56 and the contact surface 20 of the first block 12 is flush with the distal surface 56, as shown in FIGS. 10A-10B and described further below.

FIG. 10A is an isometric view and FIG. 10B is a medial view showing the first block 12 attached to the distal femur 52 of FIGS. 9A-9B in preparation for making anterior and posterior chamfer cuts on the surface of the distal femur 52. The first surface 16 of the first block 12 provides a guiding surface for making an anterior-chamfer cut along an anterior-chamfer plane 62. To make the anterior-chamfer cut, a bone cutting device such as a saw (not shown) is applied to the surface 16 of the first block 12 and advanced toward the distal surface 56 along the plane 62 until an anterior-chamfer bone portion 64 is removed. In a similar manner, the second surface 18 of the first block 12 provides a guiding surface for making a posterior-chamfer cut along a posterior-chamfer plane 66. To make the posterior-chamfer cut, a cutting device is applied to the surface 18 of the first block 12 and advanced toward the distal surface 56 along plane 66 until a posterior-chamfer bone portion 68 is removed. In one embodiment, holes (not shown) can be made to the distal surface 56 through which pins (not shown) could be inserted through holes 28 of the first block 12 and into the holes of the surface 56. In another embodiment, self-drilling bone pins (not shown) can be used which don't require holes to be predrilled into the surface 56. In both cases, the first block can be more firmly secured to the distal surface 56 which may reduce the possibility of movement of the first block during the cutting process. As explained above, the anterior-chamfer cut is made and then the posterior-chamfer cut is made. However, the sequence of cuts could be reversed with the posterior-chamfer cut being made first and the anterior-chamfer cut being made second.

FIG. 11A is an isometric view and FIG. 11B is a medial view showing the distal femur of FIGS. 10A-10B after the anterior and posterior chamfer cuts have been made. Once the anterior-chamfer cut has been made, an anterior-chamfer surface 70 remains. Likewise, once the posterior-chamfer cut has been made, a posterior-chamfer surface 72 remains. The distal femur 52 is now ready to have the second block attached to the first block 12 and to have the anterior and posterior cuts made as shown in FIGS. 12A-12B and explained below.

FIG. 12A is an isometric view and FIG. 12B is a medial view showing the distal femur of FIGS. 11A-11B with the second block 14 being attached to the first block 12. The second block 14 is advanced toward the first block 12 with the contact surface 34 of the second block facing the cutting surface 16 of the first block and the contact surface 36 of the second block 14 facing the cutting surface 18 of the first block. The second block 14 is oriented with the protrusions 44 of the second block being aligned with the holes 24 of the first block 12. The second block 14 is then advanced toward the first block 12 until the protrusions 44 of the second block 14 enter the holes 24 of the first block 12 and the blocks interlock, as shown in FIGS. 13A-13B and described further below.

FIG. 13A is an isometric view and FIG. 13B is a medial view showing the first block 12 and second block 14 being interlocked to form a cutting block assembly for making anterior and posterior cuts on the surface of the distal femur 52. As explained above, the cutting assembly 10 has an interlocking feature which allows the blocks 12, 14 to be interlocked to each other and to correlate the four distal femur cuts (anterior-chamfer, posterior-chamfer, anterior, posterior) to each other. In this manner, the accuracy of the cuts may be increased. The anterior cutting surface 30 of the second block 14 provides a guiding surface for making an anterior cut along an anterior plane 74. In a similar manner, the posterior cutting surface 32 of the second block 14 provides a guiding surface for making a posterior cut along a posterior plane 78.

As explained above, the cutting block assembly 10 has a cutting surface verification feature which provides the ability to verify the accuracy of the posterior and anterior chamfer cuts before the anterior and posterior cuts are made. Thus, before the anterior and posterior cuts are made, the second block 14 can be used to check or verify the accuracy of the anterior and posterior chamfer cuts previously made by the first block 12. For example, as explained above, the second block 14 has extended portions 30 a, 32 a which extend beyond the contact surface 20 and cutting surfaces 16, 18 of the first block 12 and onto the chamfer surfaces 70, 72. The extended portions 30 a, 32 a provide a user with a visual indication of whether the chamfer surfaces have been properly cut. If any of the chamfer surfaces 70, 72 have been improperly cut, for example, having uneven or skewed surfaces, then a gap or space will be present between the chamfer surfaces and the extended portions 30 a, 32 a indicating that cuts have been improperly made. In this case, a user can proceed to take remedial action such as reapplying the saw to the chamfer surfaces to attempt to fix the imperfections.

However, if the chamfer surfaces 70, 72 have been properly cut, then no gap or space will be present between the chamfer surfaces and the contact surfaces of the extended portions 30 a, 32 a indicating that the cuts have been properly made. In this case, a user can proceed to make the anterior and posterior cuts using the second block 14. To make the anterior cut, a bone cutting device is applied to the surface 30 of the second block 14 and advanced toward anterior bone portion 76 and along plane 74 until the anterior bone portion 76 is removed. To make the posterior cut, a cutting device such as a saw is applied to the surface 32 of the second block 14 and advanced toward a posterior bone portion 80 and along surface 78 until the posterior bone portion 80 is removed. In one embodiment, the anterior cut can be made first and the posterior cut can be made second. However, in another embodiment, the posterior cut can be made first and the anterior cut can be made second.

FIG. 14A is an isometric view and FIG. 14B is a medial view showing the distal femur of FIGS. 13A-13B after the anterior and posterior cuts have been made on the surface of the distal femur. As explained above, the extended cutting surfaces 30, 32, which are part of extended portions 30 a, 32 a, provide increased cutting surface area for making the anterior and posterior cuts. As a result, the accuracy of the anterior and posterior cuts may be improved. Once the anterior cut has been made, an anterior surface 82 remains. Likewise, once the posterior cut has been made, a posterior surface 84 remains. At this point in the surgical procedure, the four cuts (anterior-chamfer, posterior-chamfer, anterior, posterior) have been made and the cutting block assembly 10 can be removed as a single unit from the distal femur as shown in FIG. 15 and explained further below.

FIG. 15 is a medial view showing the distal femur 52 after the four cuts have been made and the cutting assembly has been removed. The distal femur 52 shows the distal cut 56 and the four cuts (anterior-chamfer 70, posterior-chamfer 72, anterior 82, posterior 84) made by the cutting block assembly of the present application. The distal femur 52 is now ready for further procedures including the implantation of a knee prosthesis using conventional techniques.

Referring to FIGS. 16-20, shown is a cutting block assembly generally denoted as 100 in accordance with another embodiment of the present invention. The cutting block assembly 100 comprises a first block 112 capable of interlocking with a second block 114 to form a four-in-two (4-in-2) cutting block assembly for resecting a portion of a bone such as a distal femur. The cutting block assembly 100 is similar to the cutting block 10 above. For example, referring to FIGS. 16-20, the first block 112 is a generally triangular shaped block forming an anterior-chamfer cutting surface 116, a posterior-chamfer cutting surface 118, a contact surface 120 and side surfaces 122. The contact surface 120 includes protrusions 126 adapted to fit into holes in the distal femur (not shown). The first block 112 also may include angled pin holes 128 extending outwardly from the contact surface 120 to the side surfaces 122. The second block 114 is a generally trapezoidal shaped block with V-shaped portion 115 sized to receive the V-shaped portion 113 of the first block 112. The second block 114 forms an anterior cutting surface 130, a posterior cutting surface 132, contact surfaces 131, 133 and side surfaces 138. The cutting block assembly 100 has many of the same features as the cutting block 10 above. For example, the cutting block assembly 100 provides an interlocking mechanism for detachably securing the blocks 112, 114 to each other. Also, the cutting block assembly 100 can be made of relatively lightweight material to provide many of the same advantages as in assembly 10.

However, unlike the second block 14 of the cutting block assembly 10 of FIGS. 1-7 above, the second block 114 of the cutting block assembly 100 of FIGS. 16-20 does not include extended portions 30 a, 32 a. Instead, the second block 114 includes an anterior contact surface 131 and a posterior contact surface 133. The anterior contact surface 131 is adapted to make contact with the anterior portion of the distal surface of the distal femur (not shown) and the posterior contact surface 133 is adapted to make contact with the posterior portion of the distal surface of the distal femur. In addition, the cutting block assembly 100 can be used for resecting a distal femur similar to the procedure described above in the context of cutting block assembly 10 of FIGS. 1-7, except that the sequence of the cuts is reversed, as explained below in detail. That is, with the cutting block assembly 100, the anterior and posterior cuts are made first and then the anterior and posterior chamfer cuts are made second.

Referring to FIGS. 21-27, a description is provided of a surgical procedure for resecting a distal femur 152 of a femur bone 150 using the cutting block assembly 100 of FIGS. 16-20 in accordance with another embodiment of the present application. This procedure is similar to the procedure explained with reference to FIGS. 9A-9B to 15A-15B in the context of cutting block assembly 10, except that the order of the cuts are reversed and the cutting block assembly 100 is attached to the distal femur as a single unit, as explained below. Referring to FIG. 21, the distal femur 152 has an anterior portion 152 a and a posterior portion 152 b. In an initial step of the surgical procedure, a distal cut is made which involves the resection or removal of a distal bone portion (not shown) from the distal femur 152 leaving behind a generally flat resected distal surface 156. Once the distal cut has been made, pilot holes (not shown) can be drilled into the distal surface 156 in precise location and orientation as known to one skilled in the art to accommodate the protrusions 126 of the first block 112. In this embodiment, the first block 112 is attached to the second block to form cutting block assembly 100. In this regard, the cutting block assembly 100 is to be attached to the distal femur as a single unit. The contact surface 120 of the first block 112 is oriented to face the distal surface 156 of the distal femur. The first block 112 is also oriented with the protrusions 126 of the first block being aligned with the holes (not shown) of the distal surface 156. In addition, the second block 114 is oriented with the contact surface 131 facing the anterior portion of the distal surface 156 and the contact surface 133 facing the posterior portion of the distal surface. The cutting block assembly 100 is advanced as a single unit toward the distal surface 156, in the direction shown by arrow 188, until the protrusions 126 enter the holes (not shown) of the distal surface 156 and the contact surface 120 of the first block 112 and the contact surfaces 131, 133 are flush with the distal surface 156, as shown in FIG. 22 and described further below.

FIG. 22 shows the cutting block assembly 100 attached to the distal femur 152 of FIG. 21 in preparation for making anterior and posterior cuts on the surface of the distal femur 152. In one embodiment, pins 129 could be inserted through holes of the first block 112 and into the holes of the distal surface 156 to more firmly secure the assembly 100 to the distal surface 156. The first surface 130 of the second block 114 provides a guiding surface for making an anterior cut along an anterior plane 174. To make the anterior cut, a bone cutting device (not shown) is applied to the surface 130 of the second block 114 and advanced toward the distal surface 156 along the plane 174 until an anterior bone portion 176 is removed. In a similar manner, the second surface 132 of the second block 114 provides a guiding surface for making a posterior cut along a posterior plane 178. To make the posterior cut, a cutting device (not shown) is applied to the surface 132 of the second block 114 and advanced toward the distal surface 156 along plane 178 until a posterior bone portion 180 is removed. In another embodiment, the sequence of cuts could be reversed with the posterior cut being made first and the anterior cut being made second.

FIG. 23 shows the distal femur of FIG. 22 after the anterior and posterior cuts have been made. Once the anterior cut has been made, an anterior surface 182 remains. Likewise, once the posterior cut has been made, a posterior surface 184 remains. The second block 114 can now be detached from the first block 112 in preparation for making the anterior and posterior chamfer cuts as shown in FIG. 24 and explained below.

FIG. 24 shows the distal femur of FIG. 23 with the second block 114 being detached from the first block 112. The second block 114 is moved away from the first block 112, in the direction shown by arrow 190, with sufficient force to detach the second block from the first block but with the first block remaining attached to the distal femur. Once the second block 114 has been removed, the distal femur 152 is ready to have the anterior and posterior chamfer cuts made as shown in FIG. 25 and explained below.

FIG. 25 shows the first block 112 attached to the distal femur 152 ready for making anterior and posterior chamfer cuts on the surface of the distal femur 152. The anterior cutting surface 116 of the first block 112 provides a guiding surface for making an anterior-chamfer cut along an anterior plane 162. In a similar manner, the posterior cutting surface 118 of the first block 114 provides a guiding surface for making a posterior-chamfer cut along a posterior plane 166. To make the anterior-chamfer cut, a bone cutting device is applied to the surface 116 of the first block 112 and advanced toward anterior bone portion 164 and along plane 162 until the anterior bone portion 164 is removed. To make the posterior-chamfer cut, a cutting device is applied to the surface 118 of the first block 112 and advanced toward a posterior-chamfer bone portion 168 and along surface 166 until the posterior-chamfer bone portion 168 is removed. In another embodiment, the posterior-chamfer cut can be made first and the anterior-chamfer cut can be made second.

FIG. 26 shows the distal femur of FIG. 25 after the anterior and posterior chamfer cuts have been made on the surface of the distal femur. Once the anterior-chamfer cut has been made, an anterior-chamfer surface 170 remains. Likewise, once the posterior-chamfer cut have been made, a posterior-chamfer surface 172 remains. At this point in the surgical procedure, the four cuts (anterior-chamfer, posterior-chamfer, anterior, posterior) have been made and the first block 112 can be detached from the distal femur by removing the pins 129 from the first cutting block and distal femur and moving the first block 112 away from the distal femur in the direction shown by arrow 192.

FIG. 27 shows the distal femur 152 of FIG. 26 after the four cuts have been made and the cutting assembly has been removed. The distal femur 152 shows the distal cut 156 and the four cuts (anterior-chamfer 170, posterior-chamfer 172, anterior 182, posterior 184) made by the cutting block assembly 100 of the present application. The distal femur 152 is now ready for further procedures including the implantation of a knee prosthesis using conventional techniques.

The cutting block devices of the present application may provide various advantages. The cutting block device is a four-in-two (4-in-2) cutting block assembly which may improve accuracy in the preparation of the distal femur for the implantation of a knee prosthesis. The cutting block assembly comprises a first block for making the anterior and posterior chamfer cuts and a second block for making the anterior and posterior cuts. The first and second blocks interlock which may help improve the correlation between the four cuts and improve the accuracy of the cuts. In one embodiment, the second block includes extended surfaces which may help improve the accuracy of the anterior and posterior cuts. In addition the extended surfaces of the second block may help provide a visual indication of the accuracy of the chamfer cuts before the anterior and posterior cuts are made. Moreover, the cutting block can be made of polymeric material which may help reduce the cost of manufacture and may improve the handling of the cutting block during a surgical procedure.

Referring to FIGS. 28-33, shown is a cutting block assembly generally denoted as 200 in accordance with another embodiment of the present invention. The cutting block assembly 200 comprises a first block 230 capable of being attached to a second block 232 to form a four-in-one (4-in-1) cutting block assembly as a single unit for resecting a portion of a bone such as a distal femur. The cutting block assembly 200 is similar to the cutting block 100 above. For example, referring to FIGS. 28-33, the first block 230 is a generally triangular shaped block having a first anterior chamfer cutting surface 204 for providing a cutting surface for making an anterior chamfer cut and a first posterior chamfer cutting surface 212 for making a posterior chamfer cut. The second block 232 is a generally trapezoidal shaped block with a V-shaped portion sized to receive the V-shaped portion of the first block 230. The second block 232 has an anterior cutting surface 240 providing a cutting surface for making an anterior cut and a posterior cutting surface 238 for providing a cutting surface for making a posterior cut. The first block 230 includes a contact surface 220 with protrusions 224 extending therefrom adapted to fit into holes in the distal femur (not shown). The second block 232 includes protrusions 228 spaced apart and sized to fit into holes 226 of the first block 230 to allow the blocks to be attached to each other. The cutting block 200 has a proximal end 231, which is adapted to face the distal femur, comprising a flat surface 220 of the first block 230 and a flat surface 222 of the second block 232. The cutting block 200 has a distal end 233, opposite the proximal end, comprising surface 242 and recess 207 of the second block 232.

However, unlike the cutting block 100 above, the block assembly 200 is a four-in-one (4-in-1) cutting block because the first block 230 and the second block 232 are intended to be attached to each other to form a single unit whereas the cutting block assembly 100 is a four-in-two (4-in-2) cutting block where the first and second blocks are intended to be detachably attached to each other. However, it will be appreciated that the cutting block assembly 200 can also be a 4-in-2 cutting block assembly by making the first and second blocks 230, 232 detachably attached to each other.

The cutting block assembly 200 is also different from the cutting block assembly 100 as described below. As best shown in sectional view in FIG. 33, the cutting block assembly 200 includes a first slot 202 to allow anterior chamfer cuts to be made and a second slot 210 to allow posterior chamfer cuts to be made on a distal end of a femur.

The first slot 202 is formed from the first anterior chamfer cutting surface 204 of the first block 230 and a second anterior chamfer cutting surface 206 of the second block 232. The anterior cutting surfaces 204, 206 are generally parallel to each other and spaced apart sufficient to accommodate the blade of a bone cutting device such as a saw. The first slot 202 extends from an opening 203 at the proximal end 231 of the cutting block 200 to an opening 205 at the distal end 233 of the cutting block. The opening 205 is formed from a generally V-shaped recess 207 at the front surface 242 of the second block 232 to accommodate a blade of a bone cutting device such as a saw. The second block 232 includes a third anterior chamfer cutting surface 208 which extends the cutting surface provided by the first slot 202 to help improve the accuracy of the cuts during the resection process. The first anterior chamfer cutting surface 204 and the third anterior chamfer cutting surface 208 are disposed on the same plane.

In a similar manner, the second slot 210 is formed from the first posterior chamfer cutting surface 212 of the first block 230 and a second posterior chamfer cutting surface 214 of the second block 232. Like the anterior chamfer cutting surfaces 204, 206 of the first slot 202, the posterior chamfer cutting surfaces 212, 214 of the second slot are generally parallel to each other and spaced apart sufficient to accommodate the blade of a bone cutting device such as a saw. The second slot 210 extends from an opening 211 at the proximal end 231 of the cutting block assembly 200 to the opening 205 at the distal end 233 of the cutting block. The second block 232 includes a third posterior chamfer cutting surface 216 which extends the cutting surface provided by the second slot 210 to help improve the accuracy of the cuts during the resection process. The first posterior chamfer cutting surface 212 and the third posterior chamfer cutting surface 216 are disposed on the same plane.

A description is now provided of a method of manufacturing the cutting block 200 of FIGS. 28-32 in accordance with an embodiment of the present application. The first block 230 and the second block 232 can be manufactured separately and then attached to each other to form single cutting block assembly 200. The blocks can be made from materials well known in the art. In one embodiment, the blocks 230, 232 can be made of a polymeric material using injection molding techniques and attached to each other using an adhesive bond, ultrasonic weld or well known techniques in the art. When using injection molding techniques, channels 236 (FIG. 30) are formed in the second block 232. In another embodiment, the blocks 230, 232 can be made from a metal material using milling techniques and attached to each other using weld bond or other techniques well known in the art. In other embodiments, the blocks can be attached to each other using mechanical locking means such as clamps, pin/socket arrangements or other locking mechanisms well known in the art. Thus, the blocks can be manufactured separately and then attached to other to form a single cutting block unit using standard manufacturing equipment. This helps reduce the cost of manufacture. In addition, such techniques may provide a surgeon with the flexibility of using an open faced cutting guide or a captured cutting slot during surgical procedures.

Referring to FIG. 34, a description is provided of a surgical procedure for resecting a distal femur 252 of a femur bone 250 using the cutting block assembly 200 of FIGS. 28-33 in accordance with an embodiment of the present application. Because the cutting block assembly 200 is a 4-in-1 block, the distal femur can be resected using fewer steps compared to the procedure using the 4-in-2 block 100 described above. As described below, the cutting block 200 is simply attached to the distal femur 252 and then the required cuts are made.

Turning to the surgical procedure, in an initial step, a distal cut is made to the distal femur which involves the resection or removal of a distal bone portion (not shown) from the distal femur 252 leaving behind a generally flat resected distal surface 256. Once the distal cut has been made, pilot holes (not shown) can be drilled into the distal surface 256 in precise location and orientation as known to one skilled in the art to accommodate the protrusions 224 of the first block 230. In this embodiment, the first block 230 is attached to the second block 232 to form a pre-assembled cutting block assembly 200 during the manufacturing process. In this regard, the cutting block assembly 200 is attached to the distal femur as a single unit. The contact surface 220 of the first block 230 is oriented to face the distal surface 256 of the distal femur. The first block 230 is also oriented with the protrusions 224 of the first block being aligned with the holes (not shown) of the distal surface 256. The cutting block assembly 200 is then attached to the distal surface 256 using the protrusions 224.

Once the cutting block 200 is attached to the distal femur 256, the cutting block can be used to make the required cuts. It is contemplated that the cuts can be made in any order. In a preferred embodiment, the anterior and posterior cuts are made first and then the anterior-chamfer and posterior-chamfer cuts are made. In a first step, a blade of a bone cutting device (not shown) is applied to the anterior cutting surface 240 and advanced toward the distal surface 256 along anterior plane 274 with sufficient force to remove an anterior bone portion. In a similar manner, a posterior cut can be made by applying the blade of the cutting device to the posterior cutting surface 238 and advancing the blade toward the distal surface 256 along posterior plane 278 with sufficient force to remove a posterior bone portion. Next, an anterior chamfer cut can be made by inserting the blade of the cutting device through the opening 205 of the first slot 202 (FIG. 33) at the distal end 233 of the block 200 and advancing the blade toward the distal surface 256 along plane 262 with sufficient force until an anterior chamfer bone portion is removed. The blade can then be retracted from the slot 202 ready for another cut such as the posterior chamfer cut. As such, the blade of the cutting device can then be inserted into the second slot 210 and advanced toward the distal surface 256 along plane 266 with sufficient force until a posterior chamfer bone portion is removed. At this point, all of the required cuts have been made and blade can then be retracted from the second slot 210.

At this point in the surgical procedure, the four cuts (anterior-chamfer, posterior-chamfer, anterior, posterior) have been made and the cutting block assembly 200 as a single unit can be detached from the distal femur. The resultant distal femur is similar to the resected femur shown in FIG. 27 as described above in the context of cutting block assembly 100. The distal femur 252 is now ready for further procedures including the implantation of a knee prosthesis using conventional techniques.

FIGS. 35-38 show a cutting block assembly according to another embodiment of the present application. The cutting block assembly comprises a third block 300 attached to the cutting block assembly 200 of FIG. 28 for use in a surgical procedure. The third block 300 in combination with the block 200 allows anterior and posterior cuts to be captured during a surgical procedure. The third block 300 is a generally ring-shaped structure with an interior opening 302 sized and shaped to receive a portion of the distal end 233 of the cutting block assembly 200 sufficient to provide a secure coupling thereto. The third block 300 has a first surface 304 facing the anterior cutting surface 240 and a second surface 306 facing the posterior cutting surface 238. The surfaces 304, 240 are spaced apart to form an anterior slot 312 extending from the distal end 308 of the third block 300 to the proximal end 310 of the third block. Likewise, the surfaces 306, 238 are spaced apart to form a posterior slot 314 extending from the distal end 308 of the third block 300 to the proximal end 310 of the third block.

As such, the slots 312, 314 of the third block are adapted to capture the anterior and posterior cuts, respectively, in a manner similar that the slots 202, 210 are adapted to capture the anterior chamfer and posterior chamfer cuts, respectively of the cutting block assembly 200. The third block 300 is an optional component which can be used by a surgeon to capture the anterior and posterior cuts during a surgical procedure. The third block 300 can be attached to the cutting block assembly 200 using techniques similar to those used to attach the blocks which form the cutting block assembly described above or other techniques known in the art. For example, in one embodiment, the third block 300 has a plurality of ridges 316 (two are shown, but each interior wall can have such ridges) located on the interior surfaces facing the side surfaces of the cutting block assembly 200 which have corresponding grooves to provide a coupling mechanism to attach the assembly 200 to the block 300. Also, the third block 300 can be made using techniques and materials similar to those used to make the blocks of the cutting block assembly 200 described above.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. 

1. A cutting block assembly for resecting a distal femur, the cutting block assembly comprising: a first block having a first outer surface forming a first anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, a second outer surface forming a first posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur, and at least one hole therein; and a second block having a recess for receiving the first block, the second block having a second anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, a second posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur, an anterior cutting surface for providing a guiding surface for making an anterior cut on the femur, a posterior cutting surface for providing a guiding surface for making a posterior cut on the femur, and at least one protrusion adapted to engage the at least one hole of the first cutting block to couple the first cutting block and the second cutting block together; the first anterior chamfer cutting surface and the second anterior chamfer cutting surface are spaced to form a first slot for making an anterior chamfer cut on the femur, the first posterior chamfer cutting surface and the second posterior chamfer cutting surface are spaced to form a second slot for making a posterior chamfer cut on the femur, and the at least one hole in the first block and the at least one protrusion of the second block being positioned beyond lateral ends of the first and second slots.
 2. The cutting block assembly of claim 1, wherein the second block further comprises a third anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, the third anterior chamfer cutting surface is disposed adjacent the first slot.
 3. The cutting block assembly of claim 2, wherein the third anterior chamfer cutting surface and the first anterior chamfer cutting surface are disposed on the same plane.
 4. The cutting block assembly of claim 1, wherein the second block further comprises a third posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur, the third posterior chamfer cutting surface is disposed adjacent the second slot.
 5. The cutting block assembly of claim 4, wherein the third posterior chamfer cutting surface and the first posterior chamfer cutting surface are disposed on the same plane.
 6. The cutting block assembly of claim 1, wherein the cutting block assembly has a first end adapted to face the distal femur and a second end opposite the first end, wherein at least one of the first and second slots extends between the first end and the second end.
 7. The cutting block assembly of claim 1, wherein at least one of first and second slots includes a first opening at one end adapted to face the distal femur and a second opening at a second end opposite the first end.
 8. The cutting block assembly of claim 1, wherein at least one of the first and second slots is sized to accommodate a cutting device blade.
 9. The cutting block assembly of claim 1, further comprising one or more protrusions extending from a surface of the first block sized and spaced to fit into holes extending into one or more surfaces of the distal femur to detachably couple the first block to the distal femur.
 10. The cutting block assembly of claim 1, wherein the first block is attached to the second block to form a four-in-one single unit cutting block assembly.
 11. The cutting block assembly of claim 1, wherein at least one of the first and second blocks is made of at least one of a polymeric material and a metal material.
 12. The cutting block assembly of claim 1, wherein the first block is attached to the second block using at least one of an adhesive bond, an ultrasonic bond, and a weld bond.
 13. A cutting block assembly for resecting a distal femur, the cutting block assembly comprising: a substantially triangular first block having a first anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, a first posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur; and a second block receiving the first block, the second block having a second anterior chamfer cutting surface spaced from the first anterior chamfer cutting surface to form a first slot between the first anterior chamfer cutting surface and the second anterior chamfer cutting surface for making an anterior chamfer cut on the femur, a second posterior chamfer cutting surface spaced from the first posterior chamfer cutting surface to form a second slot between the first posterior chamfer cutting surface and the second posterior chamfer cutting surface for making a posterior chamfer cut on the femur, an anterior cutting surface for providing a guiding surface for making an anterior cut on the femur, and a posterior cutting surface for providing a guiding surface for making a posterior cut on the femur.
 14. A cutting block assembly for resecting a distal femur, the cutting block assembly comprising: a first block having a first outer surface forming a first anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, a second outer surface forming a first posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur, and at least one hole therein; and a second block having a recess for receiving the first block, the second block having a second anterior chamfer cutting surface for providing a guiding surface for making an anterior chamfer cut on the femur, a second posterior chamfer cutting surface for providing a guiding surface for making a posterior chamfer cut on the femur, an anterior cutting surface for providing a guiding surface for making an anterior cut on the femur, a posterior cutting surface for providing a guiding surface for making a posterior cut on the femur, and at least one protrusion adapted to engage the at least one hole of the first cutting block to couple the first cutting block and the second cutting block together; the first anterior chamfer cutting surface and the second anterior chamfer cutting surface are spaced to form a first slot for making an anterior chamfer cut on the femur, the first posterior chamfer cutting surface and the second posterior chamfer cutting surface are spaced to form a second slot for making a posterior chamfer cut on the femur, and the at least one hole in the first block and the at least one protrusion of the second block being positioned beyond lateral ends of the first and second slots; further comprising a third block having a first surface spaced apart from the anterior cutting surface to form a third slot for making an anterior cut on the femur, and a second surface spaced apart from the posterior cutting surface to form a fourth slot for making a posterior cut on the femur. 